Shuttle Reference
Manual
Space Transportation
System
Space Shuttle Requirements
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The Shuttle will transport cargo
into near Earth orbit 100 to 217 nautical miles (115 to 250 statute
miles) above the Earth. This cargo -- or payload -- is carried in a
bay 15 feet in diameter and 60 ft long.
Major system requirements are
that the orbiter and the two solid rocket boosters be reusable.
Other features of the Shuttle:
- The orbiter
has carried a flight crew of up to eight persons. A total of 10 persons
could be carried under emergency conditions.
- The basic mission
is 7 days in space.
- The crew compartment
has a shirtsleeve environment, and the acceleration load is never
greater than 3 Gs.
- In its return
to Earth, the orbiter has a cross-range maneuvering capability of
1,100 nautical miles (1,265 statute miles).
The Space Shuttle is launched
in an upright position, with thrust provided by the three Space Shuttle
engines and the two SRBs. After about 2 minutes, the two boosters are
spent and are separated from the external tank. They fall into the ocean
at predetermined points and are recovered for reuse.
The Space Shuttle main engines
continue firing for about 8 minutes. They shut down just before the craft
is inserted into orbit. The external tank is then separated from the orbiter.
It follows a ballistic trajectory into a remote area of the ocean but
is not recovered.
There are 38 primary Reaction
Control System (RCS) engines and six vernier RCS engines located on the
orbiter. The first use of selected primary reaction control system engines
occurs at orbiter/external tank separation. The selected primary reaction
control system engines are used in the separation sequence to provide
an attitude hold for separation. Then they move the orbiter away from
the external tank to ensure orbiter clearance from the arc of the rotating
external tank. Finally, they return to an attitude hold prior to the initiation
of the firing of the Orbital Maneuvering System (OMS) engines to place
the orbiter into orbit.
The primary and/or vernier RCS
engines are used normally on orbit to provide attitude pitch, roll and
yaw maneuvers as well as translation maneuvers.
The two OMS engines are used to
place the orbiter on orbit, for major velocity maneuvers on orbit and
to slow the orbiter for reentry, called the deorbit maneuver. Normally,
two OMS engine thrusting sequences are used to place the orbiter on orbit,
and only one thrusting sequence is used for deorbit.
The orbiter's velocity on orbit
is approximately 25,405 feet per second (17,322 statute miles per hour).
The deorbit maneuver decreases this velocity approximately 300 fps (205
mph) for reentry.
In some missions, only one OMS
thrusting sequence is used to place the orbiter on orbit. This is referred
to as direct insertion. Direct insertion is a technique used in some missions
where there are high-performance requirements, such as a heavy payload
or a high orbital altitude. This technique uses the Space Shuttle main
engines to achieve the desired apogee (high point in an orbit) altitude,
thus conserving orbital maneuvering system propellants. Following jettison
of the external tank, only one OMS thrusting sequence is required to establish
the desired orbit altitude.
For deorbit, the orbiter is rotated
tail first in the direction of the velocity by the primary reaction control
system engines. Then the OMS engines are used to decrease the orbiter's
velocity.
During the initial entry sequence,
selected primary RCS engines are used to control the orbiter's attitude
(pitch, roll and yaw). As aerodynamic pressure builds up, the orbiter
flight control surfaces become active and the primary reaction control
system engines are inhibited.
During entry, the thermal protection
system covering the entire orbiter provides the protection for the orbiter
to survive the extremely high temperatures encountered during entry. The
thermal protection system is reusable (it does not burn off or ablate
during entry).
The unpowered orbiter glides to
Earth and lands on a runway like an airplane. Nominal touchdown speed
varies from 184 to 196 knots (213 to 225 miles per hour).
The main landing gear wheels have
a braking system for stopping the orbiter on the runway, and the nose
wheel is steerable, again similar to a conventional airplane.
There are two launch sites for
the Space Shuttle. Kennedy Space Center (KSC) in Florida is used for launches
to place the orbiter in equatorial orbits (around the equator), and Vandenberg
Air Force Base launch site in California will be used for launches that
place the orbiter in polar orbit missions.
Landing sites are located at the
KSC and Vandenberg. Additional landing sites are provided at Edwards Air
Force Base in California and White Sands, N.M. Contingency landing sites
are also provided in the event the orbiter must return to Earth in an
emergency.
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